POSTER SESSION 4
10:30–12:30, Thursday, September 17
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ABSTRACT 1244 | POSTER 184
VARIABILITY IN THE LIGHT ABSORPTION COEFFICIENTS OF PHYTOPLANKTON, NAP AND CDOM IN EUROPEAN COASTAL WATERS OVER THE LAST 30 YEARS
Coastal ecosystems play a major role in global biogeochemical cycles but remain challenging for ocean color satellite observations due to independent variability in phytoplankton, non-algal particles (NAP), and colored dissolved organic matter (CDOM). Field measurements and satellite match-ups are still required to assess multi-sensor satellite products and optimize bio-optical inversion algorithms. For this purpose, reflectance, absorption and backscattering of coastal waters must be documented together with the concentration, composition and size of optically-active water constituents. As a part of the Tara-Europa and HyperBOOST projects, stations were sampled over the wide diversity of European coastal waters in terms of physical, optical and bio-optical properties. This dataset complements and updates historical knowledge established over the last three decades.
In this study, we report the light absorption properties of phytoplankton, NAP and CDOM. Our results show distinct CDOM contributions from Atlantic to Mediterranean waters, with CDOM dominating the non-water absorption budget in most regions. Concerning phytoplankton, the B95 model (Bricaud et al.,1995) reproduces the overall spectral shape but exhibits regional biases, with over and underestimation. These results highlight limitations in current parameterizations under contrasting optical regimes. On the other hand, a new parameterization is performed to retrieve phytoplankton size fraction contributions in European coastal waters. The mass-specific absorption coefficient of NAP (aNAP*) reflects variability in particle assemblages and river inputs, with a systematic significant contribution in the near-infrared part of the spectrum. Overall, our results provide improved constraints on regional optical variability and contribute to refining bio-optical models in complex coastal environments.
Paola Potin, LOV-CNRS-SU, [email protected], https://orcid.org/0009-0002-2612-7715
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
